CDL Permit Test Guide

To get a commercial driver’s license (CDL), you first pass written knowledge tests and get a commercial learner’s permit (CLP), then pass a skills test. This guide covers which knowledge tests you need, how they’re scored and what happens next. The tests are given by your state’s driver licensing agency, so also read your state’s CDL manual for state-specific rules.

Which tests you need

Test	Who takes it	Usual number of questions
General Knowledge	Everyone	50
Air Brakes	Most Class A and B drivers, unless you accept an air brake restriction	25
Combination Vehicles	Class A	20
Hazardous Materials	Drivers who want the H endorsement	30

Other endorsements, such as tank vehicles, doubles/triples, passenger and school bus, have their own tests. Question counts depend on your state.

Passing score

Most states require 80% to pass each test. On a 50-question General Knowledge test, that means at least 40 right.

After you pass: the CLP and training

Passing the knowledge tests gets you a commercial learner’s permit. Federal rules require you to hold it for at least 14 days before taking the skills test. First-time Class A and Class B applicants must also complete entry-level driver training (ELDT) with a provider on FMCSA’s Training Provider Registry before the skills test. For the hazmat endorsement, the hazmat training must be finished before you take the Hazardous Materials knowledge test.

How hard is the CDL permit test?

The questions are drawn from the CDL manual, so they’re very learnable, but the 80% passing line leaves little room for guessing. Air Brakes trips up the most people because it’s technical: the parts of the system, the pressure numbers and the order of the pre-trip air brake check all need to be memorized.

How to study

1. Read your state’s CDL manual sections for each test you need.
2. Take practice tests until you’re scoring well above 80% every time.
3. Drill Air Brakes separately. Learn the components, the warning pressures and the air brake check steps.
4. Take the tests together if your state allows it, while the material is fresh.

A week of steady study is enough for many people for General Knowledge; give Air Brakes and Combination Vehicles a few extra days.

Start with free practice on the home page.